1. Technical Field
The present invention relates to cleaning systems, and more particularly relates to a laser based ablation method for cleaning generator and turbine components.
2. Related Art
Maintaining and cleaning large-scale turbine and generator components (referred to collectively as xe2x80x9cpower generation componentsxe2x80x9d) such as those found in power generation plants, represent a significant operational cost. The combination of intense stresses placed on the components and contaminations introduced into the components requires that such large-scale systems follow a strict maintenance schedule. Unfortunately, this results in these machines being taken xe2x80x9coff-linexe2x80x9d for a period of time for servicing. Every hour of downtime results in significant lost revenue, particularly in power generation plants and the like. Accordingly, the need for quick and efficient cleaning techniques for turbine and generator components remains an ongoing challenge.
Cleaning generator or turbine components may for instance require a complete disassembly, e.g., removal of the turbine from its housing, removal of the rotating field from the stator core, etc. The process of completely disassembling such a machine is a complex and expensive process. In the past, effectively cleaning certain components without a complete disassembly was almost impossible given that a foreign material (e.g., blast media) would need to be introduced, therefore potentially contaminating other parts of the machine.
Exemplary components requiring cleaning include turbine blades, the generator stator core, rotating field coils, rotor forging, retaining rings, etc. Cleaning involves removing dust, oily deposits, combustion deposits and other surface contamination. For example, turbine parts, such as turbines blades may require the removal of built up debris that is reducing the overall efficiency of the machine. Past methods for cleaning such parts typically included a high-pressure application of aluminum oxide, glass bead, or CO2.
Cleaning generator parts often involves removal of residual insulation and resins from the coil slots in the rotor forging and stator core when the windings are removed for a rewind. The current methods of cleaning such components are essentially manual, e.g., using scrapers made of TEXTOLITE(trademark), wiping with rags soaked in approved cleaning solutions, and polishing with a clean dry rag. Likewise, if the rotor coils are to be reused, removal of insulation and resins from the coils is also required. Rotor forging and rotor coils to be reused are often cleaned by blasting with glass beads. Rotor coils wrapped with glass mica tape can also be cleaned by heating in an oven to burn off the tape and subsequently cleaned with approved solvents and rags.
The above-described methods are not only labor intensive, but also pose an environmental hazard. For example, the process of removing and disposing of the used glass beads and corncob, as well as processes related to collecting and disposing of the contaminated rags after cleaning create environmental waste. Workmen are exposed to hazardous chemical cleaners and are subjected to potential exposure to airborne contamination of the media used for blast cleaning. The blast cleaning media can escape from the enclosure and contaminate the surrounding area. Accordingly, there exists a need to overcome the problems faced by prior approaches.
The present invention addresses the above-mentioned problems, as well as others, by providing a cleaning system and method that utilizes a portable workhead to direct a pulsed laser beam to a surface of a generator or turbine component. In a first aspect, the invention provides a laser-based cleaning system for cleaning blades of a turbine rotor assembly, comprising: a laser positioned remotely from the turbine rotor assembly for generating a laser signal; a laser workhead that receives the laser signal via an optical fiber, wherein the laser workhead is positionable proximate a blade in the turbine rotor assembly and can deliver a laser beam onto a surface of the blade to cause a cleaning of the blade; and a vacuum system for vacuuming debris created by the cleaning.
In a second aspect, the invention provides a method for laser-based cleaning of blades in a turbine rotor assembly, comprising: positioning a laser remotely from the turbine rotor assembly; mounting a robot proximate the turbine rotor assembly; providing within the robot a laser workhead that receives a laser signal from the laser via an optical fiber; positioning the workhead proximate a first turbine blade such that the workhead can deliver a laser beam onto the surface of the first blade; robotically moving the workhead along the first blade in a preprogrammed manner while the laser beam ablates the surface of first blade to effectuate a cleaning of the first blade; and vacuuming debris caused by the ablation.
In a third aspect, the invention provides a laser-based cleaning system for cleaning a rotor bore within a turbine shaft, comprising: a laser positioned remotely from the turbine shaft for generating a laser signal; a robot capable of traversing the rotor bore and directing a laser workhead at predetermined positions along the rotor bore surface; an optical fiber that delivers a laser signal from the laser to the laser workhead, wherein the laser workhead can deliver a laser beam onto rotor bore surface to cause a cleaning; and a vacuum system for vacuuming debris created by the cleaning.
In a fourth aspect, the invention provides a laser-based cleaning system for cleaning power generation components (turbine, generator, etc.), comprising: a laser workhead that receives the laser signal via an optical fiber, wherein the laser workhead is positionable proximate a component and can deliver a laser beam onto a surface the component to cause a cleaning; a laser positioned remotely from the laser workhead for generating a laser signal over the optical fiber, and a vacuum system for vacuuming debris created by the cleaning.